The Cincinnatian was a named passenger train operated by the Baltimore and Ohio Railroad. The B&O inaugurated service on January 19, 1947, with service between Baltimore, Maryland and Cincinnati, Ohio.
These cars, unlike previously re-built cars from the Baltimore and Ohio Mount Clare shops, were fully streamlined, the heavyweight cars stripped to the frame and re-built completely. Many felt these cars were as good as any cars built by the big three car builders AC&F, Budd, or P/S. The quality of the workmanship was unquestioned, but some of the interior décor was a little dated for that period. The new Cincinnatians entered service January 19, 1947 behind streamlined Presidential Pacific Locomotives painted to match the trailing train in the magnificent Blue and Gray scheme.
The Cincinnatian would have its route changed on June 25, 1950 from a Baltimore to Cincinnati daylight schedule to a Detroit to Cincinnati daylight schedule where it would remain until the creation of Amtrak. On this new routing the train sets became successful almost from the beginning.  The Cincinnatian on this route used many mail cars, which contributed to the route's success.
In 1970 and 1971, the Cincinnatian was the only Baltimore and Ohio train on the Cincinnati to Detroit route. The trains no longer offered checked baggage--passengers had to carry their own luggage on and off the coaches.
Food was not available either. The 1970 timetable said "Food and beverages may be purchased at Toledo station during station stop." That meant a long wait for hungry northbound riders who left Hamilton at 10:47 a.m. and arrived in Toledo at 2:30 p.m. Southbound, the train departed Toledo at 11:45 a.m. and stopped in Hamilton at 3:25 p.m. The B&O still was using the name and same numbers when the railroad ended passenger service on April 30, 1971. 
The following are the two consists of the Cincinnatian (1947)
5301 PRESIDENT ADAMS 4-6-2 Streamlined Pacific & Tender
1307 EDEN PARK Baggage Crew Day Room Buffet 24-seat Lounge Car
3565 INDIAN HILL 60 revenue seat Coach
3572 OAKLEY 56 Revenue seat Coach with Stewardess Room
3567 COLLEGE HILL 60 Revenue seat Coach
3304 PEEBLES CORNER 24-seat Dining 18-seat Lounge Observation
5302 PRESIDENT JEFFERSON 4-6-2 Streamlined Pacific & Tender
1308 HYDE PARK Baggage Crew Day Room Buffet 24-seat Lounge Car
3566 WINTON PLACE 60 Revenue seat Coach
3573 NORWOOD 56 Revenue seat Coach with Stewardess Room
3568 WALNUT HILLS 60 Revenue seat Coach
3305 FOUNTAIN SQUARE 24 seat Dining 18-seat Lounge Observation
BAGGAGE CREW DAY-ROOM BUFFET 24-SEAT LOUNGE COMBINATION CARS Baltimore and Ohio Mount Clare Shops, December, 1946 (Re-built and Streamlined for the CINCINNATIANS)
1307 EDEN PARK
1308 HYDE PARK
60 REVENUE SEAT COACHES Baltimore and Ohio Mount Clare Shops, December 1946 (Re-built and Streamlined for the CINCINNATIANS)
3565 INDIAN HILL
3566 WINTON PLACE
3567 COLLEGE HILL
2568 WALNUT HILLS
56 REVENUE SEAT COACHES WITH STEWARDESS ROOM Baltimore and Ohio Mount Clare Shops, December 1946 (Re-built and Streamlined for the CINCINNATIANS)
24 SEAT DINING 18-SEAT LOUNGE OBSERVATIONS Baltimore and Ohio Mount Clare Shops, December 1946 (Re-built and Streamlined for CINCINNATIANS)
3304 PEEBLES CORNERS
3305 FOUNTAIN SQUARE
Two 52 revenue seat streamlined Coaches 3574 AVONDALE and 3575 PRICE HILL were completed by Mount Clare Shops in March, 1947 and replaced 60 Revenue seat Coaches 3567 COLLEGE HILL and 3568 WALNUT HILLS in the CINCINNATIANS at that time.
52 REVENUE SEAT COACHES Baltimore and Ohio Mount Clare Shops, March 1947 (Re-built and Streamlined for the CINCINNATIANS)
3575 PRICE HILL